Like Frum, Michael Gerson attempts to defend it:
Precisely because [Romney] has a history of ideological heresy, it would be difficult for him to abandon his current, more conservative iteration. He has committed himself on key conservative issues. Having flipped, he could not flop without risking a conservative revolt. As a result, conservatives would have considerable leverage over a Romney administration.
Ed Morrissey pounces:
The most laughable assertion here … is that Romney’s record of inconsistency works as a guarantee of future consistency. That’s not an argument; it’s a rationalization. Since when has a history of political expediency been a good indicator of future principled stands?
The Dish 